<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        canvas {
            border: 1px solid #ccc;
        }
    </style>
</head>
<body>
<canvas width="600" height="400"></canvas>
<script>
    var myCanvas = document.querySelector('canvas');
    var ctx = myCanvas.getContext('2d');
    /*1.曲线的绘制
    2.线是由点构成的
    3.曲线可以由数学公式得来*/

    /*公式： y = (x+12)^2 */
    /*公式: y= sin(x)*/
    for (var i = 1; i < 600; i++) {
        var x = i;
        // var y = Math.pow(x/10-30,2);
        var y = 50 * Math.sin(x/10) + 100;
        ctx.lineTo(x,y);
    }
    ctx.stroke();

</script>
</body>
</html>
